The present invention relates generally to a marking grid for radiographic imaging and, more particularly, to a marking grid for use in computerized tomography.
Marking grids are used during radiographic imaging to provide visual reference points on the radiographic image. For example, marking grids may be used to locate the position of internal body structures or tumors relative to the reference points on the radiographic image. To use a marking grid, the marking grid is placed on or adjacent to the patient""s body while the radiographic image is taken. The marking grid creates lines or dots on the radiographic image which can be used as reference points to locate the position of body structures or tumors relative to the location of the marking grid on the patient. Marking grids are often used in computerized tomography (CT) scanning to produce reference points on the CT scan image.
Prior marking grids have been comprised of elongated radiopaque strips or members fixed to a substrate material. The substrate material in these devices has been in the form of sheets, generally without openings in the material. As a result, the marking grid must be moved to allow the radiologist to mark the patient""s skin or to insert a surgical device such as a biopsy needle. This can require multiple scans of an area to locate the biopsy needle properly.
Some prior marking devices have partially addressed this problem by providing one or more holes for inserting biopsy needles through the marking device. For example, in U.S. Pat. No. 4,860,331 to Williams et al., a marking device is described in which the substrate is perforated with widely spaced, small diameter holes to permit insertion of biopsy needles. These holes are not always in the optimal position for insertion of a biopsy needle, and the holes do not provide an adequate area for a radiologist to place necessary markings on a patient""s skin. As a result, the radiologist may have to move the marking grid for insertion of biopsy needles or marking the skin, which can result in inaccurate insertion or marking.
Accordingly, it is an object of the present invention to overcome one or more of the drawbacks or disadvantages of the prior art and to provide a marking grid for radiographic imaging that allows a radiologist to place markings on the patient""s body or insert biopsy needles in the optimum desired location selected by the radiologist.
The present invention provides a marking grid for radiographic imaging that permits the radiologist to place markings on the patient""s skin or insert a device such as a biopsy needle in an optimal location as selected by the radiologist. The marking grid is comprised of a substrate material that conforms to the patient""s skin. The substrate material is substantially radiolucent. The back side of the substrate is coated with a pressure sensitive adhesive which is used to adhere the marking grid to the patient""s skin. The marking grid can be provided on a plastic or wax coated backing.
The marking grid includes a plurality of parallel strips of a material that is at least partially radiopaque. The parallel radiopaque strips produce images, typically dots, on a radiographic image. The substrate defines elongated apertures between the strips of radiopaque material. Each aperture extends along substantially the entire length of the adjacent radiopaque strip(s).
The present disclosure also relates to an improved method for manufacturing marking grids. The substrate is provided on a releasable backing, and the releasable backing defines a plurality of holes longitudinally spaced relative to each other along at least one, and preferably both, marginal portions of the backing. The holes are engageable with means for driving the backing, such as the pins of rotatably-driven sprockets or a tractor-feed drive. Accordingly, the holes allow precise registration of the backing with a tool, such as a cutting tool for cutting the stretchable substrate, an application tool for applying glue or other adhesives to the substrate to secure the radiopaque strips thereto, or a printing tool for printing letters or other indicia on the substrate or the backing.
Among the advantages of the present invention is that the elongated apertures in the substrate allow a biopsy needle to be inserted into the patient in an optimal location without the need to remove or replace the marking grid. The present invention also provides the advantage of allowing the radiologist to place markings on a patient""s skin without moving the marking grid.
A further advantage of the present invention is that the marking grid can be produced rapidly and inexpensively.
Other advantages of the marking grid of the present invention will become readily apparent in view of the following detailed description of preferred embodiments and accompanying drawings.